Container for food products



June 23, 1931. A. E. STEVENSON 1,311,160

' CONTAINER FOR FOOD PRODUCTS Filed June 5, 1928 '2 J6 vi 7;? j

Patented June 23, 1931 UNITED STATES PATENT OFFICE ARTHUR E. STEVENSON, OF CHICAGO, ILLINOIS, ASSIGNOR TO CONTINENTAL CAN COM- PAINY, INQ, OF NEW YORK, N. Y., A GORIORATION OF NEW YORK CONTAINER FOR FOOD PRODUCTS Application filed June 5, 1928. .Serial No. 283,131.

This invention relates to improvements in containers for food products, and more articularly concerns a container forme of tin plate and coated with enamel, employ able for food products containing juices which dissolve tin and iron.

It has long been known that plain cans, or those formed of uncoated tin plate will resist the action of the juices of certain food products, such for example as cherries, strawberries, loganberries, raspberries, etc. With such plain cans, however, the tin of the plating appears to react upon the contents of the can to decolorize the food product.

In'order .to avoid such trouble, it has been sought to provide an enamel coating on the internal surface of the container by employing a usual varnish and baking. This enamel acted as a mechanical protection for the tin plate, and prevented the access of the juices to the tin platesubstantially through out the area of the internal surface; but by reasons of manufacturing difiiculties, it is found that with some cans, holes are present in this enamel coating so that the tin plate is exposed. This of itself is not disastrous to the contents of the can, but if the tin plate is imperfect opposite the hole so that the steel backing is exposed, the fruit juices rapidl attack this iron with the production of hy rogen and ultimate perforation. The hydrogen present in the can causes springing or bulging of the can. In other words, the container with its contents soon ceases to be'merchant-able goods. It has now been found that such formation of hydrogen springers or perforations can be prevented by the mixing with the varnish employed for forming the enamel, of a certain quantity of a form of tin soluble in the juices of the food product. This quantity is regulated in a manner apparent to a person skilled in the art, according to the particular varnish, its consistency, the thickness of the coating employed, etc. On the one hand, the quantity is kept relatively low so that the quantity of tin present in the food juices shall never be suflicient to affect the food product; while on the other hand the quantity is kept sufficiently large so that a protecting action is obtained upon any exposed steel or iron which maybe present upon the internal surface of the container. It is preferred to employ stannous oxide, which is excellently adapted for the purpose in view; and in practice from up to the maximum content which can be added to the coating varnish is employable, and it is found that the varnish is still mechanically workable with additions of as large as of stannous oxide. When other forms of tin materials or compounds soluble in the food juices are to be'employed, the proportions which can and may be added are easily to be determined by a person skilled in the art.

In actual test it has been found that the tin thus present acts as a protective agent, so that no perforations or hydrogen springers were present in the test containers, while Within the same time control containers reached as high as unmerchantable either by perforation or hydrogen springers.

The operation of the small proportion of soluble tin present in the enamel appears to occur by a slight solution of this tin in the food juices. If exposed iron or steel surfaces are present, there appears to be a depositing of such tin upon the naked iron or steel, thereby preventing the attack of the food juices upon such naked surfaces, and protecting them from perforation or the evolution of hydrogen thereat.

In the drawings:

Figure 1 represents a section through a can; while Fig. 2 is a corresponding view on an enlarged scale.

The drawings show a container havin the bodysides 10 and ends 11, formed 0 tin plate with the base sheet iron 12 and the tin coating 13 thereon. Within the can, the varnish coating 14 is provided in the customary way to interpose between the surface of the container and its contents and in the illustrated example for as great a portion of the surface as practically possible. As shown on an enlarged scale in Fig. 2, the varnish contains minute particles 15 of the tin compound of which some are exposed at the surface of the varnish to the action of the fruit juices which exert a slight dissolving power thereon. Where a gap 16 5 occurs in the varnish coating 14, and terminating at the layer of tin, substantially no action occurs since the maximum concentration of tin in the foodstuff is very low, owing to the very slow dissolving action occurring, and the possible presence already in the foodstuff of the tin compound dissolved from the varnish. Where a gap 17 occurs in the varnish opposite a gap 18 in the tin, so that the iron base is exposed to the juices, there would normally be a tendency for the immediate dissolution of the iron with the formation of a hydrogen springer and ultimately a perforation. Owing, however, to the presence of the tin in solution in the fruit juices, a sealing is accomplished by the depositing of tin upon the naked iron or steel so that the attack of fruit juices themselves upon such naked surfaces is prevented.

This invention, therefore, relates to the provision of a container and its formation by the depositing on the internal surface of the tin plate body of a varnish containing a quantity of tin in form soluble in the juices of the contents of the container, but in uantity insufficient to affect the food proc net, to the end of preventing the attack of the food juices upon any exposed iron or steel.

From another point of view, therefore, the protection may be apparently considered as obtained by producing within the contents of the container a small concentration of stannous ions, and maintaining such con centration at a very low value, such that the tin present does not react upon the food product; but wherein the concentration is suflicient to prevent perforations and the evolution of hydrogen in amount to form hydrogen springers by contact of the food juices with naked iron or steel surfaces.

It is obvious that the invention is not limited to the specific embodiment shown but that the material and proportions thereof may be varied in many ways within the scope of the appended claims.

Having fully described my invention, what I claim as new and desire to secure by Letters Patent, is

1. A container for food products comprising body and end portions formed of tin plate, the exposed internal portions of the container being coated with a varnish having a portion of tin in soluble form incorporated with the ingredients of the varnish, and uniformly distributed throughout the varnish prior to the application of the varnish to the metal to form the enamel coating, said soluble tin being sufficient in quantity to form a precipitate on the exposed plate so as to prevent corrosion leading to perforations or hydrogen springers, said quantity of soluble tin being insufficient to affect the food products.

2. A container for food products containing juices which dissolve tin and iron, comprising a body of tin plate having its internal surface covered by an enamel formed by baking a varnish containing a portion of stannous oxide in quantity sufficient to protect naked iron or steel surfaces, but being insufiicient to affect the food product.

3. A container for food products containing juices which dissolve tin and iron comprising a body of tin plate having its internal surface covered by a coating containing a portion of. a stannous compound, said compound being exposed to the food prod.- ucts in a quantity sufiicient to dissolve therein and produce a precipitate on any exposed iron, so as to prevent corrosion thereof leading to perforations or hydrogen springers, said quantity of soluble tin being not suflicient to aflectthe food products.

4. A container for food products containing juices which dissolve tin and iron, comprising a body of tin plate havin its internal surface substantially covere by an enamel coating, said coating having exposed to the juices a limited amount of tin in a form soluble in said juices.

5. A container for food products containing juices which dissolve tin and iron, comprising a body of tin plate in which minute gaps may occur in the tin coating, 2. layer of varnish located on the internal surface. of the bod and which may have minute gaps theret rough, wherewith a gap through the varnish coating may be alined with a gap through the tin coating whereby the iron base is exposed to the fruit juices, said varnish coating containing tin in soluble form exposed to the action of the fruit juices .whereby the tin dissolved in the fruit juices may act to form a precipitate on the exposed iron plate so as to prevent corrosion leading to perforations or hydrogen springers, said quantity of exposed tin being insufiicient to affect the food products.

In testimony whereof, I afiix my signature.

ARTHUR E. STEVENSON. 

